Such wormholes are defined by two free functions. We choose the first one by relating the radial pressure \(p\)  to the tangential pressure \(\tau \)  such as \(p=-\tau \) . The perfect fluid is then isotropic as a cosmological fluid (other choices of perfect fluid are possible with \(p\ne  -\tau \)  as in [1]}, [2]}, [3]}, [4]}). Such fluids are interesting for several reasons. In particular, they are generally (not always) physically motivated and constrained by observations such as the supernovae and the CMB. Another reason is the possibility that a ghost dark energy could both rules the Universe expansion and forms static spherically symmetric wormholes naturally, a possibility that we discard in this paper for some of the most common dark fluids used in the literature. The second free function can be the wormhole energy density, its pressure, its spatial shape, its gravitational redshift, etc. We let it free when studying general properties of the phase space and we specify it when examining some particular wormhole models.
